Greed

You show your spectators a one dollar bill. Fold it in half and it's still a one dollar bill. Give it a wave and with no funny moves it visually changes into a five dollar bill. That's phase one, and your spectators already got their money's worth.
Fold it again and it's still a five dollar bill. But give it a wave... and with no funny moves the five visually changes into a ten dollar bill! That's phase two. Fold the bill again. It's still a ten dollar bill. Give it a wave and again it visually changes, this time into a twenty dollar bill!
You give the folded up twenty dollar bill a shake and it visually morphs into a fifty...